How does NEC4 clause 15 work?

Clause 15 deals with problems before they become compensation events, and it carries a price for ignoring it. Under clause 15.1 the Contractor and the Project Manager each give an early warning by notifying the other as soon as either becomes aware of any matter which could increase the total of the Prices, delay Completion, delay meeting a Key Date, or impair the performance of the works in use. Under clause 15.2 the Project Manager keeps the Early Warning Register, enters each matter on it, and instructs the first early warning meeting. Under clause 15.3 those at the meeting co-operate in making and considering proposals for avoiding or reducing the effect of the matter, seek solutions that bring advantage to all affected, decide on the actions to be taken and who takes them, and decide which matters can be removed from the register. Under clause 15.4 the Project Manager revises the register after each meeting and issues it. An early warning is not a notification of a compensation event and does not replace one; they are separate communications with separate consequences. The cost of not warning sits in clause 61.5 and clause 63. If the Project Manager decides that the Contractor did not give an early warning of the event which an experienced contractor could have given, it notifies that decision and the compensation event is assessed as if the warning had been given. Cost that a timely warning would have avoided is left out of the assessment, and under Options C to F cost incurred only because the warning was not given is also Disallowed Cost. What goes wrong: early warnings are treated as admissions or claims and so are not given; Contractors assume the compensation event notification does the job; the register is never revised, so decisions are lost; and the clause 61.5 decision arrives with no record of what the warning would have changed.